Delayed neurological deterioration following anoxia is known to result from carbon monoxide exposure. However, it may also occur with anoxia of other types as well. The present report describes a case of delayed postanoxic encephalopathy with bilateral striatal lesions demonstrated by magnetic resonance imaging. A 27-year-old man exhibited anoxic anoxia caused by upper airway obstruction following general anesthesia for shoulder fracture surgery. Initially he was delirious and markedly excited for one day and became apparently normal for the following three days. Then he relapsed into delayed neurological deterioration with speech and gait disturbance, clumsiness of hand, pyramidal signs and metamorphopsia. Thereafter, he became bed-ridden and fell into semicomatose state with marked motor restlessness, involuntary movement of the tongue and decorticate posture. Twenty-five days later he had a second recovery period after hyperbaric oxygenation that lead to the sequelae with speech and motor disturbances and mild mental changes. I examined the present case as an expert witness in a civil suit eleven years after initial anoxia. The patient showed slight intellectual impairment and personality change. Impairment in figure-ground differentiation and disorders of spatial thought were also observed. Neurological examination revealed anisocoria, dysarthria with acquired stuttering, disturbances of fractionated movement of fingers, writer's cramp and Babinski's sign bilaterally. Postural dystonia of both hands and fingers, rigidity and spasticity of all extremities were also present. Magnetic resonance imaging (MRI) showed bilateral lesions of the corpus striatum, especially of the putamen. Some portion of the caudate nucleus was also involved. Cerebral cortices and white matter were slightly atrophic. From the above clinical course and neurological findings, we diagnosed the present case as delayed postanoxic encephalopathy. Ginsberg (1979) noted that in cases of anoxia not related to carbon monoxide, diffuse demyelinative changes of cerebral hemispheral white matter tended to be associated with relapsing clinical course, and gray matter injury was only seen in a few cases. MRI findings in the present case suggest that main site of the lesion to be in gray matter of the corpus striatum. In this respect, the present case is considered to be noteworthy.